function setCanvasStyle(map) {
    let size = 100;
    let canvas = document.createElement("canvas");

    let ctx = canvas.getContext("2d");
    //设置半径
    canvas.width = size;
    canvas.height = size;
    /* 25 */
    let radius = size / 4;
    /* 25~35 */
    let increase = true;
    function draw() {

        ctx.clearRect(0, 0, canvas.width, canvas.height)
        ctx.beginPath()
        ctx.arc(size / 2, size / 2, radius, 0, Math.PI * 2);
        ctx.closePath();
        ctx.fillStyle = "#652e80";
        ctx.fill();
        if (radius > 50) {
            increase = false;
        } else if (radius < 25) {
            increase = true;
        }
        if (increase) {
            radius++;
        } else {
            radius--
        }
        setTimeout(draw, 20);
        /* mapbox render */
        map.render();
    }
    /* 绘制 */
    draw();
    /* 将创建的canvas元素作为openlayer的样式实现了 */
    let style = new ol.style.Style({
        image: new ol.style.Icon({
            img: canvas,
            imgSize: [canvas.width, canvas.height]
        })
    })
    return style;
}